1. Field of the Invention
The present invention concerns a filter unit, especially for purifying air, with a number of adsorbent filter elements, each of which contains activated carbon as the absorbent material.
2. Description of the Related Art
The present invention also concerns the use of this air purification filter unit, especially for producing high-purity air and for removing gaseous substances, foul-smelling substances, and toxic substances from air streams, for example, in ventilation plants, ventilation systems, air-conditioning systems, or the like.
Finally, the present invention concerns plants or systems, especially ventilation plants, ventilation systems, or air-conditioning systems, for purifying air or for producing or conditioning air with this filter unit.
The pollution of the environment by harmful substances has been receiving more and more public attention due to increasing environmental awareness and the availability of highly sensitive analytical methods.
Moreover, increasing industrialization has resulted in extensive pollution of the atmosphere. Every type of combustion process, e.g., in power plants, automobile engines, heating systems, etc., produces undesired combustion products, especially oxidized carbon compounds, nitrogen oxides, incompletely combusted hydrocarbons, and the like.
Other sources of harmful substances include contaminated rooms that contain building materials that contain harmful substances (e.g., building materials that contain PCB's, etc.). Toxic substances can also be released from pieces of furniture, wall paints, carpet adhesives, and the like.
In addition, there is now a growing danger of terrorist attacks involving the systematic introduction of toxic substances into the air-conditioning systems of buildings, subway ventilation systems, etc.
All together, therefore, there is a great need to remove a very wide variety of air pollutants from the air, especially harmful or annoying noxious substances, toxic substances, or foul-smelling substances. Many state-of-the-art methods are available for removing such substances. Examples that might be mentioned here include mechanical filtration methods, methods that involve the reaction or destruction of the annoying or harmful substances, and absorption and adsorption methods.
Adsorption methods involve the use of filter units that work by adsorption. The problem here is that the adsorption capacity of state-of-the-art filter units is often inadequate and thus relatively quickly exhausted, so that the filter materials have to be replaced. Furthermore, state-of-the-art adsorption filter units often lack sufficient “spontaneity” or adsorption kinetics, with the result that breakthroughs can occur. In addition, state-of-the-art adsorption filter units often have inadequate adsorption efficiency and are not universally suitable for the adsorption of a very wide variety of harmful and toxic substances.